DE1088641B - Process for bonding cast polyurethane polymers to metal - Google Patents

Description

GERMAN

PATENT OFFICE

KL.22i 2

INTERNATIONAL KL.

C09j; C08g

ANME LDETAG:

NOTICE THE REGISTRATION AND ISSUE OF THE EDITORIAL:

G 26994 IVa / 22i

May 6, 1959

SEPTEMBER 8, 1960

The invention relates to methods for bonding polyurethane polymers to metals.

Elastomeric polyurethane products made by reacting polyisocyanates and polymers have been that - such as polyesters, polyester amides and polyalkylene ether glycols - implementable Containing hydrogen atoms are known. Elastomeric polyurethane foams, solid, processable polyurethane rubbers and liquid ones Reaction mixtures that can be cast into shaped products have also been described been.

The pourable reaction mixtures are e.g. B. made of polyesters that are either at room temperature are liquid or can be melted at relatively low temperatures and those with polyisocyanates and preferably a diisocyanate and a crosslinking agent such as Water, a glycol or a diamine. If necessary, others can non-reactive components, such as fillers or coloring agents, are added. In addition to the excellent physical properties in ge ^ - hardened state, the advantage of such casting compounds is that they can be used in relatively simple, Molded easily and without the application of high temperatures and pressures usually encountered when deforming used by rubber products made from solid natural or synthetic rubbers can be hardened.

Examples of molded products made from liquid, pourable, reaction mixtures are solid tires for technical purposes, seals, gears, reinforced adjustment belts, bushings and other machine components including metal reinforced molded parts for automobiles. The bond strength of these castable urethane compositions to metals is even for most purposes adequate without the use of adhesives. However, when the metal reinforced part increased tem- '40 is exposed to temperatures, the adhesive strength of the elastomer to metal has not always been satisfactory proven. Premature failure of the part usually occurs at high temperatures Separation of the rubber from the metal.

To improve the adhesive strength of these polymers to metals in the heat, a process has become known in which two treatments with a binder are carried out. A first adhesive ("cement") is applied to the metal surface, which must be dried and hardened, then a second adhesive ("cement") is applied directly to the first, previously hardened binder, which in turn is dried and hardened for gluing
of cast polyurethane polymers with metal

Applicant:

The Goodyear Tire & Rubber Company,
Akron, Ohio (V. St. A.)

Representative: Dipl.-Ing. W. Meissner,

Berlin-Grunewald, Herbertstr. 22

and Dipl.-Ing. H. Tischer, Munich 2, patent attorneys

Claimed priority:
V. St. v. America dated May 21, 1958

the must, whereupon finally the elastomeric polymer on the surface of the second binder is poured.

It has now been found that a simplified adhesive composition that uses only one adhesive is used to achieve improved hot bond strength between certain castables Polyurethane conversion mixtures and metal can be used.

This is used to produce the high-temperature-resistant bonds between the polyurethane elastomers described above and the metal used adhesive according to the invention is a mixture of (A) a resinous copolymer of SO to 80 percent by weight Styrene and 50 to 20 percent by weight of acrylonitrile and (B) polyisocyanates, which are in the U.S. Patent 2,683,730 and polyurethane mixtures of the formula

OCN-R- (CY ₂ -R'-NCO) _n

in which R and R 'are arylene radicals, Y is hydrogen, an alkyl or aryl radical and η is an integer, these mixtures containing at most 40% of the diisocyanate.

The polyurethane reaction products used as the elastomeric ingredient in the bonding process of the invention to be used are made by adding o-dichlorobenzidine, which is used as a crosslinking agent acts, S ^ '- dimethyl - ^' - diphenylene diisocyanate, that

009 590/391

3 4

acts as a curing agent, and a liquid poly- gluing the polyurethane elastomers with metals, such as ester are implemented, which of at least one di-iron, aluminum, steel, stainless steel, zinc carboxylic acid and at least one glycol made of plating, brass and other alloys and a molecular weight of 1500 to applies.

2500, a hydroxyl number of 45 to 75 and an acid number of not more than 5 in the production of layer structures. The implementation of the gluing process of the invention is the metal product of o-dichlorobenzidine, 3,3'-dimethyl-4,4'- surface preferably first by degreasing, diphenylene diisocyanate and the polyester provides a chemical cleaning treatment and / or cured polyurethane composition, which is opposite Softening cleaned by ball or sandblasting. After deforming and deforming at elevated temperatures, the cleaning of the metal surface will result in its resistance resistance being marked. The polyisocyanate mixtures are prepared in a process, e.g. By dipping, spraying, to which the condensation products of primary aryl or brushing can be applied. The monoamine and aliphatic or aromatic adhesive is then allowed to dry, whereupon aldehydes or ketones are phosgenated. When the liquid polyurethane reaction mixture is poured against the molar ratio of amine to aldehyde or ketone treated metal surface with the binder limited to a range of 4: 2.5 to 4: 3.5 and allowed to cure. Although the poly is and the amine is also present in the larger molar amount of the urethane reaction mixture at room temperature, the phosgene can harden during the subsequent phosgene, the layer structure is preferably obtained from a polyisocyanate mixture in which a tetnpedas diisocyanate in 20 15 minutes to a few hours a 40 percent by weight not heated from 100 to 150 ° C,
excess amount is included. Preferred poly- The polyesters used in the preparation of the polyurethane elastoisocyanate mixtures used as adhesives are those which are obtained when the polyamines are obtained when the condensation reaction of one or more of the condensation reactions of aniline 25 carboxylic acids and one or more are digested several glycols with formaldehyde, benzaldehyde, acetaldehyde, and methyl. Examples of dicarboxylic acids, ethyl ketone or acetone; of o-toluidine with form- aldehyde, benzaldehyde, methyl ethyl ketone or acetone used in the manufacture of these polyesters; are: succinic, glutaric, adipic, o-anisidine with formaldehyde, benzaldehyde, pimelic, cork, azelaic and sebacic acid. From acetaldehyde, methyl ethyl ketone or acetone; and of these acids, adipic and α-naphthylamine with formaldehyde, benzaldehyde, sebacic acid are preferably used. Examples of glycols obtained from acetaldehyde, methyl ethyl ketone or acetone can be used to produce the polyester. It has been found that particularly good results are ethylene glycol, propylene glycol, butylene results are achieved when the polyisoglycol, pentamethylene glycol and hexamethylene glycyanate mixture, which is obtained by phosgenation of AmHn ₇ 35 kol. Ethylene glycol, propylene glycol, and mixtures of för'maldehyde condensation product produced, of which these two glycols are preferably used, which is used to produce the adhesive. As already stated above, the polyester should be used. average molecular weight from 1500 to 2500 to A particularly effective styrene-acrylonitrile-2500 and accordingly a hydroxyl number of 45. Resin useful for making the adhesive have 40 to 75 with an acid number not above 5 is a synthetic resin which is obtained by polymerizing the The specified molecular weight range comprises approximately 70 parts by weight of styrene and 30 parts by weight of polyester, which is made either at room temperature or at. parts of acrylonitrile. The weight ratio of poly-45 used for the production of the casting according to the invention in the liquid state and the hardened polymer with excellent isocyanate to styrene-acrylonitrile resin can provide internal physical properties. The half comparatively broad limits to be changed, the uppermost acid number has been given to exclude the use of 1 to 300 parts of polyester, which are mainly limited by a car-polyisocyanate mixture per 100 parts of the resin as boxyl groups and the more resinous ones are satisfactory has proven. 50 are preferably obtained as rubber-like products if they are reacted with 10 to 100 parts by weight of polyisocyanate mixtures each with a diisocyanate.
100 parts by weight of resin used, the best being the polyesters, which are obtained from Adi results with adhesives, the pinic acid and a mixture of glycols, about 50 parts by weight of polyisocyanate per 100 parts by weight of 80 mole percent ethylene glycol and 20 mole percent per part resin contain. 55 contains pylene glycol, in which the adhesive is prepared by dissolving the resin - molecular weight range of about 2000, and the polyisocyanate and the polyisocyanate in an indifferent solvent - have an acid number not above 2,
As is known, in the production of poly a reaction between the other urethane products is usually chemically influenced by an excess of di-constituents of the adhesive. 60 isocyanate is used so that the hardening of the polyesters is ensured and sufficient reaction toluene, ethylene dichloride, methyl ethyl ketone, mono sites for other constituents such as chlorobenzene and methylene dichloride are supplied. The solids - like o-dichlorobenzidine - reactive water content of the adhesive can contain between 2 and 40 substances. The amount of diisocyanate overweight percent of the total weight of the adhesive 65 shots - although not decisive - can be changed, with adhesives that are 5 to 20 percent important because the diisocyanate is the most expensive component used in the weight percent solids, the preferred reaction mixture is. Can be used poly-wise. Urethane products with exceptional properties are obtained when - based on 1 mole of the process according to the invention, the adhesive is related to the polyester - · the polyester with 0.10 to

0.80 moles of o-dichlorobenzidine and 1.25 to 2 moles of 3,3'-dimethyl-4,4'-diphenylene diisocyanate is implemented, the diisocyanate always in a molar excess of at least 10% over the total molar amount of dichlorobenzidine and polyester is used.

One in terms of physical properties the cured product and the physical properties of the liquid mixture in particular useful batch contains about 100 parts by weight of a polyester with an average Molecular weight of about 2000, about 6 parts by weight of o-dichlorobenzidine and about 23 parts by weight 3,3'-dimethyl-4,4'-diphenylene diisocyanate.

The castable polyurethane reaction mixture is prepared by bringing the polyester to a temperature heated from 100 to 140 ° C, the diisocyanate is added, the reactants 30 to 40 minutes thoroughly mixed or mixed homogeneously, the diamine crosslinking agent added and then this reactant is mixed homogeneously with the mixture for about 1 minute, whereupon the complete reaction mixture is poured into a mold or onto a surface to be watered. Even though the reaction mixture hardens even without the application of additional heat, it has been found to be advantageous proven to put the cast product in a heated air oven or the mold by some others Measures, e.g. B. in a curing press, in order to increase the curing speed of the To heat the reaction mixture.

The application of pressure during curing in the oven has not been found to be necessary or necessary proven. However, the application of pressure to products cured in a press gives favorable results.

The invention is further illustrated by the following examples, which, however, are not intended to limit the scope of the invention and, if not, in which otherwise indicated, parts are parts by weight.

example 1

A 70:30 copolymer made from a styrene-acrylonitrile resin (20 parts) was dissolved in ethylene dichloride (80 parts). A polyisocyanate mixture (20 parts) obtained by phosgenating a mixture of a polyamine resin of aniline and formaldehyde and had an amine equivalent of approximately 136) was added in 80 parts of ethylene dichloride solved. A binder was made by mixing 5 parts of the polyisocyanate solution with 95 parts of the resin solution were prepared. A zinc plated strip of metal about 1 inch (2.5 cm) wide was used

xo sandblasted and covered with a single coat of the adhesive which was then allowed to dry. A polyester (100 parts) made from adipic acid and a mixture of glycols containing 80 mole percent ethylene glycol and 20 mole percent propylene glycol, an average molecular weight of about 2000, a hydroxyl number of about 57 and an acid number of 0.8 was heated in a vacuum of 20 mm Hg at 120 ° C for 1 hour. 23 parts of 3,3'-dimethyl-4,4'-diphenylene diisocyanate were added to this polyester. The mixture was stirred ^{at a temperature of 120 °} C. under a vacuum of 20 mm Hg for 30 minutes. Then o-dichlorobenzidine (6 parts) was added and mixed with the polyester and diisocyanate for 1 minute, after which a layer of the liquid reaction mixture was poured onto the binder treated and zinc plated strip. The coated strip was heated in an air oven for 24 hours at a temperature of 121 ⁰ C and then 24 hours at room temperature, allowed to age before was started with the adhesion strength tests. Strip adhesion tests, the results of which are given in Table I, were performed on the cured sample. The same experiment was repeated using a steel strip in place of the zinc strip. Additional samples were prepared and tested using varying amounts of the resin and isocyanate solutions. The changes made and the bond strength values obtained are given in Table I, the bond strength values being given in kg, which are required to peel the elastomer over a width of 2.5 cm from the metal.

example Bindemit
Resin solution telmass
Isocyanate solution Adhesion strength
Zinc plating t on metal
stole 1 95 5 53 kg 34 kg 2 90 10 45 kg Sample broken 3 80 20th 43 kg 38.5 kg 4th 70 30th 39.4 kg 38.5 kg S. 60 40 31.3 kg 31.3 kg 6th 66 33 35.3 kg Except for
Scale at 68 kg

Besides these results, other excellent bond strength values are obtained when the Adhesives of the present invention for joining the illustrated elastomers to other metals, such as iron, aluminum or brass is used. The adhesive is special for manufacture of solid technical wheel tires effective in which the polyurethane elastomer on a metal wheel hub or a metal hoop. If these wheels are subjected to heavy loads, considerable heat is generated during use. According to the invention Procedure for gluing rubber with metal, a wheel rim is made for technical purposes, which withstands such high temperatures excellently.

Although only certain forms of execution and Details have been described can be

understandably various changes can be made without departing from the scope of the invention will.

Claims (5)

Patent claims: 1. A method for bonding cast polyurethane polymers to metal, characterized in that that on a metal surface at least one coating of an adhesive that consists of an inert solvent, a resinous copolymer of 50 to 80 percent by weight Styrene and 50 to 20 percent by weight of acrylonitrile and a polyisocyanate mixture, which is represented by the following formula OCN-R- (CY ₂ -R'- NCO) _n , in which R and R 'are arylene radicals, Y is hydrogen, an alkyl or aryl group, η is an integer, the polyisocyanate mixture containing at most 40 percent by weight of the diisocyanate, applied, the adhesive dried, and a liquid reaction mixture on the coated metal surface from (A) a polyester which has been produced from at least one dicarboxylic acid and at least one glycol, has a molecular weight of 1500 to 2500, a hydroxyl number of 45 to 75 and an acid number of not above 5, (B) o-dichlorobenzidine and ( C) 3,3-dimethyl-4,4'-diphenylene diisocyanate is applied and the reaction mixture is cured. 2. The method according to claim 1, characterized in that the liquid reaction mixture used is about 100 parts by weight of polyester, for example 6 parts by weight of o-dichlorobenzidine and about 23 parts by weight of 3,3'-dimethyl-4,4'-diphenylene diisocyanate contains. 3. The method according to claim 1 or 2, characterized in that the polyester used from Adipic acid and a mixture of glycols is made containing about 80 mole percent ethylene glycol and contains about 20 mole percent propylene glycol. 4. The method according to any one of claims 1 to 3, characterized in that compounds are used in which the groups denoted by R and R 'are phenylene groups and that Y is hydrogen. 5. The method according to any one of claims 1 to 4, characterized in that the solids content of the adhesive used between 1 and 300 parts by weight of polyisocyanate mixture per 100Ge important part of the resin. © 009 590/391 8.60